Poison oak dermatitis is a major occupational hazard in the United States, with the majority of unemployment compensation claims in California being filed for work lost due to this disease. The dermatitis is produced because the oil in the leaves, called urushiol, is composed of a mixture of catechols which can bind to skin cells. The immune system recognizes the combination of catechol-skin cells as being "foreign" and launches the same type of assault on those cells as it would on invading bacteria. This reaction produces swelling, redness, blistering, and probably destruction of the cells. The most feasible method of controlling the problem is to tolerize the immune system to the chemical. It is possible to produce partial tolerance by oral or intramuscular injection of large amounts of the urushiol oil itself, but the side effects resulting from the reaction of the immune system are too great to make this practical. Instead we are attempting to produce a chemical analog of the most active one of the catechols, which will produce tolerance without the concomitant immunity which produces the side effects. This project therefore involves both the study and the identification of the compound which is actually presented in vivo to the immune system, and a search for an analog which will produce tolerance but not immunity.